Driver assistance systems are electronic devices in motor vehicles for assisting the driver in certain driving situations. In these systems, safety aspects, but also an increase in driving comfort and mileage improvement, are frequently prioritized. Driver assistance systems intervene semi-autonomously or autonomously into a drive system, a control system (e.g., an accelerator or a brake), or into signaling systems of the vehicle or emit a warning via suitable human-machine interfaces shortly prior to or during critical driving situations.
Known driver assistance systems include, for example, anti-lock systems (ABS), electronic stability programs (ESP), automatic emergency brakes (AEB), and the like. Many driver assistance systems use radar sensors to monitor the surroundings and for distance measurement. The alignment and calibration of such radar sensors are particularly important in this case. In standards, such as ISO 26262, for example, time intervals in which the functionality of radar sensors should be ensured are established.
Since radar sensors are typically installed in or behind the bumper of a vehicle, they may become misaligned by external influences such as minor impacts during parking, falling rocks, snow load, etc., without the vehicle driver immediately noticing. Due to the great reach of such sensors, even a hardly perceivable misalignment by a small misalignment angle may become noticeable in the information which is generated by the radar sensors.
U.S. Pat. No. 7,813,851 describes a misalignment ascertaining method with the aid of which an acceleration along a directional axis, whose alignment with respect to the measuring axis of a forward-directed sensor system is fixed, is measured. The measured acceleration is compared to a predetermined limiting value. If the limiting value is exceeded, the radar sensor may be deactivated. The radar sensor may only be used again after another alignment in a repair shop, for example.